These are my 5 favorite monsters in no real order.
Love me some Godzilla. A huge fire breathing lizard created by nuclear testing. Some think he is evil, some think he simply exist. Either way he is a reminder of the folly of man.
The infamous Count Dracula. No list would be complete without the most famous vampire of them all. Many stories about what he is capable of exist but he is always dangerous and never sparkles.
Dragons, Earth cultures are full of them. From Chinese dragon gods to European knights fighting them and many many more. Many forms exist and all are powerful and ferocious and most importantly, they look really cool.
Ghost. Are they real? Who knows, but who doesn’t love a good ghost story? For thousands of years legends have persisted in every culture on Earth from Casper the friendly ghost and helpful ancestors to murderous poltergeist. Real or not they make for great movies and great campfire stories.
Release the Kraken! Possibly one if the more iconic lines in movie history. That is not why it made my list however. Sea monsters are inherently scary because even today we have no idea whats at the bottom of most of the ocean. The idea of some huge monster down there suddenly crushing your ship is just scary for anyone.
So let me know which ones you like that I missed, and may the gaming gods bring you glory.